1. Field of the Invention
Underwater viewing systems.
2. Description of the Prior Art
Television cameras are often used underwater for monitoring certain operations and for viewing underwater objects and animal life. With a monochrome TV system, objects are identified by means of brightness, size, shape and contrast. With a monochrome system however, two areas having different hues can actually show up identically on a black and white or other monochrome TV monitor.
Considerable enhancement in the visibility of objects can be obtained with the use of color TV, however a problem arises due to the fact that the water medium between the color TV camera and the scene to be viewed selectively filters the light such that the effective optical spectrum at ranges for example of 20 to 30 feet, is perhaps only half as wide as it is in air. The effect of the water is to eliminate the violet and red ends of the spectrum such that if a normal color television system were to be used to view an undersea scene containing a range of colors, only objects containing green or green components would be visible on the display. That is, objects viewed through the water appear as various brightnesses and shades of green. A more efficient interpretation of the greenish display could be achieved if the color contrast within the band of wavelengths transmitted by the water medium were increased.